code: def test_format_as_image_notransparency(catdog_rgba, mock_expl):
      # heatmap with full transparency
      overlay = format_as_image(mock_expl, alpha_limit=0.0)
      assert_pixel_by_pixel_equal(overlay, catdog_rgba)
  
imports: import pytest
  import numpy
  from eli5.base import Explanation, TargetExplanation
  from eli5.formatters.image import format_as_image, heatmap_to_image, expand_heatmap, _validate_heatmap, _update_alpha, _cap_alpha, _overlay_heatmap
  from .utils_image import assert_pixel_by_pixel_equal
label_desc: Use image node_id 22 for calling a global function with example usage: test_format_as_image_notransparency(catdog_rgba, mock_expl) without return types